Atomistic studies of interactions between the dominant lattice dislocations and γ/γ-lamellar boundaries in lamellar γ-TiAl
Atomistic studies of interactions between the dominant lattice dislocations and γ/γ-lamellar boundaries in lamellar γ-TiAl
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DOI：
10.1016/j.actamat.2009.03.042
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发表时间：
2009-06
期刊：
影响因子：
9.4
通讯作者：
I. Katzarov;A. Paxton
中科院分区：
文献类型：
--
作者：
I. Katzarov;A. Paxton
本文报道了γ-TiAl中占主导地位的晶格位错（普通螺型12 <$110]和101]超位错）与多合成孪晶（PST）TiAl中所有三种γ/γ片层晶界之间相互作用的原子模拟。本研究的目的是阐明PST TiAl中片层边界控制塑性变形的早期阶段。在我们的模拟中的原子间的相互作用所描述的键级势为L10-TiAl，它提供了一个适当的量子力学描述的键合。我们感兴趣的位错核心的几何形状，晶格产生接近层状边界和这些核心的方式受到影响的弹性和原子的影响的位错-层状边界相互作用。研究了界面对γ-片层内普通位错和超位错的激活、滑移以及塑性变形在片层间的传递的影响。我们在PST TiAl的原子尺度塑性中发现了三个新现象，特别是由于与60°和120° γ/γ界面相关的弹性和原子失配：（i）γ/γ界面的两个新作用，即，120°和60°界面内的超位错的分解和单个普通位错的随后脱离，以及（ii）普通位错被60°和120°界面阻挡，导致孪晶位错的发射。
This paper reports on atomistic simulations of the interactions between the dominant lattice dislocations in γ-TiAl (ordinary screw 12〈110] and 〈101] superdislocations) with all three kinds of γ/γ-lamellar boundaries in polysynthetically twinned (PST) TiAl. The purpose of this study is to clarify the early stage of lamellar boundary controlled plastic deformation in PST TiAl. The interatomic interactions in our simulations are described by a bond order potential for L10-TiAl which provides a proper quantum mechanical description of the bonding. We are interested in the dislocation core geometries that the lattice produces in proximity to lamellar boundaries and the way in which these cores are affected by the elastic and atomistic effects of dislocation-lamellar boundary interaction. We study the way in which the interfaces affect the activation of ordinary dislocation and superdislocation slip inside the γ-lamellae and transfer of plastic deformation across lamellar boundaries. We find three new phenomena in the atomic-scale plasticity of PST TiAl, particularly due to elastic and atomic mismatch associated with the 60° and 120° γ/γ-interfaces: (i) two new roles of the γ/γ-interfaces, i.e. decomposition of superdislocations within 120° and 60° interfaces and subsequent detachment of a single ordinary dislocation and (ii) blocking of ordinary dislocations by 60° and 120° interfaces resulting in the emission of a twinning dislocation.